1. Field of the Invention
The present invention relates to a control device of an internal combustion engine. More specifically, the present invention relates to a control device performing stop control for operating an internal combustion engine for a prescribed period after an ignition switch is turned off.
2. Description of the Background Art
Japanese Patent Laying-Open No. 2000-104651 discloses an ignition device for operating an engine for a certain time after an ignition switch is turned off. The ignition device includes an engine control unit (hereafter referred to as an “ECU”) for controlling ignition of a spark plug and fuel injection, an ignition switch, an ECU relay for supplying/cutting off operating power to the ECU, an ignition coil, a spark plug, and an ignition coil relay. The ignition switch and the ECU relay are provided in parallel between a battery power supply and the ECU. The ignition coil relay is provided between the battery power supply and the ignition coil, and receives an operation instruction from the ECU.
In the ignition device, power is supplied to the ignition coil via the ignition coil relay controlled by the ECU. When ignition by the spark plug is performed for a predetermined number of times after turning-off of the ignition switch, the ignition coil relay is turned off by the ECU.
According to the ignition device, since ignition of the spark plug is performed for a predetermined number of times after the ignition switch is turned off, operability and exhaust properties at restarting of the engine can be prevented from being deteriorated due to injected fuel which remains inside a cylinder of the engine without attaining combustion.
When an engine is stopped, there is a desire to operate the engine for a certain period after a driver turns off an ignition switch in order to set an actuator which operates using an engine oil pressure (for example, an intake and exhaust valve controlled with a VVT (Variable Valve Timing)) to a prescribed position for the next starting of the engine.
The ignition device disclosed in Japanese Patent Laying-Open No. 2000-104651 described above, in which ignition by the spark plug is performed for a predetermined number of times after the ignition switch is turned off and then the ignition coil relay is turned off by the ECU, can satisfy the desire. In the ignition device, however, since the ignition coil relay is driven by the ECU, a circuit for driving the ignition coil relay must be added to the ECU. Therefore, the ignition device increases a cost and also decreases reliability of the ECU.